Thread: Salisbury shaft upgrade needed with Detroit?

Originally Posted by Ancient Mariner

I have broken 4 axles over the years three 28 spline and one 31 spline all with
Detroits and 9"diffs have yet to see any damage to a diff or locker
In a defender you might not notice straight away keep driving and do some damage Mine were in a series with part time transfer case all when in 2wd
fairly obvious to tell .Axles were R4 heat treated to about 95-100 tons so go off with a bit of a bang

Am

Early Detroit cases were steel, I think they're iron these days ?
Can't recall if the centre/dog arrangement was steel too or not ?

Moot point anyway re the carrier as the Sals version is technically a No SPin as you use the Sals carrier

Originally Posted by Ancient Mariner

I have broken 4 axles over the years three 28 spline and one 31 spline all with
Detroits and 9"diffs have yet to see any damage to a diff or locker
In a defender you might not notice straight away keep driving and do some damage Mine were in a series with part time transfer case all when in 2wd
fairly obvious to tell .Axles were R4 heat treated to about 95-100 tons so go off with a bit of a bang

Am

When I first fitted a 31 spline 3.5:1 9" Ford F100 rear (new shortened 1974 casing flanged for LR stubs, hubs, brakes, salisbury flanges) to the rear of my 109 LR hybrid (+250HP 302, New Process NP435 F350 gearbox mated to 2A transfer case) in 1976 it had a Limited Slip centre. We made Hi-Tuff axles and ran one set unhardened while two other sets were off for treatment. In about 1980 I fitted a Detroit centre.

While not recommended as Hi-Tuff is in the annealed state for machining it ran on that pair of axles for quite a while - then one night after the Detroit was fitted one side sheared neatly near the flange end (part of our brilliant design). I drove home quite a few miles on ONE rear axle. This takes a bit of getting used to as it dives one way on acceleration and the other way on backing off! Next day took off both the rear hubs, stubs etc to fit the correctly hardened, straightened and peined and polished treated axles and have had them in for years. The 31 Spline axles won't pass through the stub axle tubes. The Detroit centre was from an early 1970 ex-Bathurst race car and had been run in other races before it went into the LR.

The only problem was that the driving flanges regularly got chewed out and then the axle would spin in the "hole". Jack Macnamara used to broach worn out ten spline flanges to 24 spline for me. Also the driving flange bolts would work loose. We determined later that when the casing was flanged that it was not axially true ie the two axles came to a different centre point and as the Detroit was firm in that position the only thing that could give was wearing away the splines. Eventually the casing was pulled out, straightened with a setup dummy centre and then the flanges faced again. Never had the problems since and making sure the casing was perfectly straight almost removed the "banging " that these diffs were famous for. You should see the look on some sports car owner's face when you slow up at lights on a curve, come to a stop, release the brakes and the diff goes off! "BANG".

Bob

Great pics 101 Ron, cheers. I'm thinking the Detroits in the Fire Appliances are not a soft locker. We run two Isuzu's in our CFS Brigade. The older FFR drives a lot nicer than the new Isuzu. I think this is partly due to the fact that the new 34 appliance is full time four wheel drive, with selectable ctr diff lock. Between acceleration/deceleration under drive around corners the Detroit makes for a very uncomfortable drive (only at low speeds). When responding or at reasonable road speed it's not noticeable. The Detroit is also very 'vocal' at times when returning from a job or training once warm, it will often let out a large bang as we swing back into the car park. Seeing your pics makes me think ours might end up looking the same!! Wondering now if our Bulk Water Carrier also has Detroits (6x4 Isuzu with Allison Auto), as that thing really likes to carry straight on in the soft stuff! It'll be interesting to see how it goes in the 130! The first trip to the VHC in April will have to be with STD shafts as loosing shafts as well as lockers in the joint account in 1 month just ain't gonna happen!!!!

Originally Posted by bobslandies

When I first fitted a 31 spline 3.5:1 9" Ford F100 rear (new shortened 1974 casing flanged for LR stubs, hubs, brakes, salisbury flanges) to the rear of my 109 LR hybrid (+250HP 302, New Process NP435 F350 gearbox mated to 2A transfer case) in 1976 it had a Limited Slip centre. We made Hi-Tuff axles and ran one set unhardened while two other sets were off for treatment. In about 1980 I fitted a Detroit centre.

While not recommended as Hi-Tuff is in the annealed state for machining it ran on that pair of axles for quite a while - then one night after the Detroit was fitted one side sheared neatly near the flange end (part of our brilliant design). I drove home quite a few miles on ONE rear axle. This takes a bit of getting used to as it dives one way on acceleration and the other way on backing off! Next day took off both the rear hubs, stubs etc to fit the correctly hardened, straightened and peined and polished treated axles and have had them in for years. The 31 Spline axles won't pass through the stub axle tubes. The Detroit centre was from an early 1970 ex-Bathurst race car and had been run in other races before it went into the LR.

The only problem was that the driving flanges regularly got chewed out and then the axle would spin in the "hole". Jack Macnamara used to broach worn out ten spline flanges to 24 spline for me. Also the driving flange bolts would work loose. We determined later that when the casing was flanged that it was not axially true ie the two axles came to a different centre point and as the Detroit was firm in that position the only thing that could give was wearing away the splines. Eventually the casing was pulled out, straightened with a setup dummy centre and then the flanges faced again. Never had the problems since and making sure the casing was perfectly straight almost removed the "banging " that these diffs were famous for. You should see the look on some sports car owner's face when you slow up at lights on a curve, come to a stop, release the brakes and the diff goes off! "BANG".

Bob

good info sounds like everything old is new again

I take it the ford housing was set up with the diff center offset to the drivers side like LR are? And when you say the 31 spline shafts would not pass through the stub, do you mean the spline end wouldnt but the wasted main section of the shaft would?

all in all pretty cool set up, even if you were still running the weak LR t/case and leaf springs

It is interesting how views on lockers change over time. The current thinking is that lockers can load up axles and cause breakages when all drive is essentially transferred to just one axle and it twists or snaps with the load of the vehicle acting on it.

When I first got into 4wding in the late 60s the thought was the opposite and the prevailing thought was that lockers would protect axles from breakage. It was thought that without lockers the wheel with least traction would start spinning and if it gripped on rock or something similar the wheel would suddenly stop spinning snapping the axle with the shock load where having a difflock fitted would stop the wheel spinning in the first place and there would be no shock loads on the axle.

I guess that both positions have an element of truth.

Garry

The diff from the series 2 31 spline Detroit 4140 stub axles bigger bore bigger
bearings custom hubs and discs Set up for divorced Inter Transfer case

Originally Posted by uninformed

good info sounds like everything old is new again

I take it the ford housing was set up with the diff center offset to the drivers side like LR are?
Yes

And when you say the 31 spline shafts would not pass through the stub, do you mean the spline end wouldnt but the wasted main section of the shaft would?

Yes, the main diameter of the axles was the same as the 24 spline Salisbury so it would pass through the stub axles but the stock was turned down from a larger diameter to spline the larger 31 spline. This way if there was a breakage it would be away from the diff centre at the root diameter of the spline near the flange. As the flanges then either wore away or cracked through to the deeply grooved section where the diameter changes on the earlier Series flanges there were no problems thereafter.

all in all pretty cool set up, even if you were still running the weak LR t/case and leaf springs

In those days it was all we could use but I did later try to get a Chevrolet Blazer transfer case and ended up with the wrecker in California sending an alloy one instead of the steel one I wanted! End of that idea. Took teeth off two intermediate gears in the transfer case but drove more carefully after that.

I forgot to mention the original NP435 Ford mainshaft was replaced with an International 10 spline SAE larger diameter output mainshaft compared to the Ford (I think it was a C6 auto size - about 30 splines and a devil to replicate for the spud shaft into the TC).

Next year it will get back on the road as the tow vehicle (he hopes).

Bob

Originally Posted by rick130

Early Detroit cases were steel, I think they're iron these days ?
Can't recall if the centre/dog arrangement was steel too or not ?

Moot point anyway re the carrier as the Sals version is technically a No SPin as you use the Sals carrier

Whatever they were made from in the 1970s the manufacturers were very confident about their quality as I remember they had a 100,000 mile replacement warranty.

Bob